Implantable vertebral frame systems and related methods for spinal repair

ABSTRACT

A system for performing surgical repair of the spine includes a distractor and a permanently implanted bone plate system. A surgical repair methodology is also disclosed that employs an implanted bone plate system with a substantially void internal volume which is attached to adjacent vertebrae subsequent to the distraction and adjustment of curvature of the vertebrae and prior to the excision of disc and/or end plate tissue through the bone plate. The device further facilitates the subsequent delivery of an interbody repair device for the purpose of either fusion or dynamic stabilization, such as by disc arthroplasty. The plate may be permanently implanted, such as when a fusion between the attached vertebral bodies is desired, but it need not be permanently implanted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.11/855,124 entitled “Implantable Bone Plate System and Related Methodfor Spinal Repair”, filed Sep. 13, 2007, and to U.S. Provisional PatentApplication Ser. No. 60/954,511 entitled “Implantable Bone Plate Systemand Related Method for Spinal Repair”, filed Aug. 7, 2007. Each patentapplication is incorporated herein by reference in its entirety.

The present invention relates to a system for performing surgical repairof the spine, such as for but not limited to the delivery of aninterbody repair device for the purpose of either fusion or dynamicstabilization.

BACKGROUND

It is current practice in spinal surgery to use bone fixation devices toimprove the mechanical stability of the spinal column and to promote theproper healing of injured, damaged or diseased spinal structures.Typically, corrective surgery entails the removal of damaged or diseasedtissue, a decompression of one or more neural elements, followed by theinsertion of an intervertebral implant for the purposes of a fusion ordisc arthroplasty. In cases where spinal fusion is the desired surgicaloutcome, the final step is often to apply a bone plate in order toimmobilize adjacent vertebral bones to expedite osteogenesis across saidvertebral segments.

Most current surgical techniques require that damaged vertebral tissuebe placed under rigid axial distraction throughout much of theprocedure. This allows for greater ease in the removal of tissue,provides a larger working space for instrument maneuverability, enhancesthe surgeon's visibility and assists with the fit of the interbodyimplant once the distractor apparatus is removed. Conventionaldistraction of the spine typically employs the use of temporary“distractor pins” placed directly into the bone tissue adjacent to thedisc space to be repaired, which are subsequently induced to moveaxially by the attachment and adjustment of a secondary tool. Analternative method employs the use of a ratcheting spreader device whichis inserted directly into the vertebral interspace and is adjustedthereafter to achieve desired distraction. These distraction methodsoffer an imprecise means to restore preferred vertebral alignment, addseveral steps, require more time to install and remove, increase therisk for entwining of surrounding vascular structures or peripheralnerves and can present significant physical impediments and technicalchallenges to the surgeon. Additionally, because the distractor deviceremains temporarily inserted during the decompression and fusionportions of the procedure, the surgeon must essentially work around theobtrusive projecting devices while completing the majority of thesurgery.

It is also known that current distraction methods, while generally notdesigned or intended for this purpose, are often employed to adjust ormaintain the angular alignment of adjacent vertebra in an attempt torestore normal lordotic curvature. The outcomes are varied, the degreeof distraction and the angular correction produced by currentdistraction methods are often imprecise, require substantial subjectiveassessment by the surgeon and can vary significantly from patient topatient. Further, excessive distraction can result in a negativesurgical outcome which can result in nerve damage or on-going postsurgical pain for the patient.

There is a high degree of dimensional variability in the resultingintervertebral volume after distraction has been achieved using thesedevices. As a result, the surgeon must often make “trial and error”assessments as to the size and shape of the interbody implant to beinserted and may be required to customize the implant intraoperativelyprior to final insertion.

In the conventional method, once the implant has been inserted, thedistractor device is removed and the vertebrae can be secured by theattachment of a bone plate. Such bone plates, including a plurality ofbone screws, are applied near the completion of the procedure to providevertebral fixation and prohibit undesirable migration of theintervertebral implant.

Several design constructs have already been proposed in which a deviceis applied to adjacent vertebrae at the start of a procedure, prior totissue removal, for the purposes of achieving and maintaining preferredvertebral alignment while serving also to constrain tissue removalthroughout the procedure. The disclosed or published art in this methodcan generally be categorized into two broad categories: removabledevices and permanently implantable devices.

The removable devices differ from the present proposed invention in thatthe devices used to maintain preferred vertebral alignment are temporaryinserts and are subsequently removed after tissue removal so that arepair device may be delivered thereafter. The prior art which disclosespermanently implantable devices differs in that the devices functionsolely to maintain preferred vertebral alignment and are not part of acomprehensive system and related method to precisely control andpermanently maintain the preferred spatial relationship of adjacentvertebral members for controlled tissue removal and delivery of a repairdevice.

Removable Devices

U.S. Pat. No. 7,153,304 entitled Instrument System for Preparing a DiscSpace Between Adjacent Vertebral Bodies to Receive a Repair Device,issued Dec. 26, 2006 to Robie et al., discloses a removable instrumentsystem for preparing a disc space between adjacent vertebral bodiesusing a series of distractors that restore natural lordosis before atemporary template is attached for vertebral immobilization and tofunction as a guide for an insertable reamer meant for tissue removal.

U.S. Pat. No. 7,083,623 to Michelson, entitled Milling Instrumentationand Method for Preparing a Space Between Adjacent Vertebral Bodies,issued Aug. 1, 2006, discloses a removable milling device and method forpreparing a space between adjacent vertebral bodies which essentiallymaintains preferred vertebral alignment while functioning as a saw guideto control bone and soft tissue removal.

US Pat. App. 2005/0043740 to Haid, entitled Technique andInstrumentation for Preparation of Vertebral Members, published Feb. 24,2005, discloses a removable instrumentation set and technique forpreparation of vertebral members utilizing a docking ring which istemporarily applied to the anterior spine to maintain preferredvertebral alignment and to function as a docking plate for anarticulating bone removal device.

U.S. Pat. No. 7,033,362 to McGahan, entitled Instruments and Techniquesfor Disc Space Preparation, issued Apr. 25, 2006, discloses a removableinstrumentation set and method for disc space preparation whereby anintervertebral device is temporarily inserted for the purpose ofconstraining tissue removal and guiding the position of anintervertebral repair device.

US Pat. App. 2003/0236526 to Van Hoeck, entitled Adjustable SurgicalGuide and Method of Treating Vertebral Members, published Dec. 25, 2003,discloses a removable surgical guide and method with adjustablefunctionality for the preparation of adjacent vertebra.

US Pat. App. No. 2006/0247654 to Berry, entitled Instruments andTechniques for Spinal Disc Space Preparation, published Nov. 2, 2006,discloses a removable milling instrument assembly for vertebral endplatepreparation which constrains a cutting path obliquely oriented to theaxis of the vertebra.

Permanently Implanted Devices

US Pat. App. 2004/0097925 to Boehm, entitled Cervical Spine StabilizingSystem and Method, published May 20, 2004, discloses a permanentlyimplantable spine stabilizing system and method whereby a plateconfigured to be positively centered along the midline is placed toretain adjacent vertebra in a desired spatial relationship duringdiscectomy and fusion procedures. The disclosed invention uses a seriesof temporary implants and removable drill templates in an attempt toassure the alignment of the implanted device along the midline of thespinal column. This alignment is typically not considered to besignificant in determined the clinical outcome of the procedure and isfurther considered impractical for the purposes of performing repairprocedures on multiple adjacent disk spaces due to the normal scolioticcurvature of the spine.

US Pat. App. 2005/0149026 to Butler et al., entitled Static and DynamicCervical Plate Constructs, published Jul. 7, 2005, describes animplanted cervical bone plate having a graft window located between thebone screw holes for the purposes of providing visualization and accessto an intervertebral implant. The device described is applied after theintervertebral space has been repaired and after the implant has beenpositioned. The specification states specifically that an appropriately“sized dynamic plate is placed over the inserted bone implant”;thereafter the bone plate is located with respect to the implant byviewing the implant through the graft window and secured in place usingbone screws.

Additional bone plate devices are disclosed in U.S. Pat. No. 3,741,205to Markolf et al, and US Pat. Apps. 2005/0149026 to Butler et al. and2007/0233107 to Zielinski.

Accordingly, it is apparent that there remains a need for and advantageto a permanently implantable spinal repair system and related methodwhereby the final preferred vertebral alignment and fixation occursprior to the surgical removal of damaged tissue, without the use oftemporary implants or fasteners and where the surgical procedures can beperformed there-through in the minimum amount of time with the minimumnumber of entries into the surgical field. It is further apparent thatthere is a need for a system wherein subsequent recovery procedures canbe performed with minimal effort should implantation fail or shouldsubsequent surgery be required.

SUMMARY OF THE DISCLOSURE

The invention relates generally to systems and methods for establishingand securing adjacent vertebrae in a defined spacial relationship priorto the excision and repair of damaged tissue. In one embodiment, thesystem includes at least one distraction device, at least oneimplantable vertebral frame, at least one interbody repair implant, andat least one retention member. In this embodiment, the distractiondevice is configured for temporary placement between adjacent vertebraefor achieving a desired spatial relationship between the vertebrae. Inthis embodiment, the implantable vertebral frame is configured to spanbetween the adjacent vertebrae, the frame being configured to attach toeach of the adjacent vertebra while the distraction device is in placeto postoperatively maintain the desired spatial relationship between thevertebrae after the distraction device is removed, the frame also havingat least one internal operating aperture there-through for providingaccess to at least one intervertebral disk space. In this embodiment,the interbody repair implant is sized in relationship to the aperture ofthe frame to fit there-through and into the intervertebral space. Andfinally, in this embodiment, the retention member is attachable to theframe to cover at least a portion of the aperture.

In various embodiments of the above summarized system, the frame mayassume various forms and include various features that will now besummarized. In some embodiments of the system, the frame may beconfigured to span between and remain postoperatively attached to atleast three adjacent vertebrae. In some embodiments of the system, theframe may include external walls having integrally manufacturedretractor blade engaging features. In some embodiments of the system,the frame may have a plurality of through holes to facilitate attachmentof the frame to adjacent vertebrae by means of bone screws. In some ofthese particular embodiments, the holes may be a combination ofelongated slots and circular holes to accommodate the insertion of bonescrews there-through into vertebral bone tissue. In some embodiments ofthe system, the frame may have a plurality of protrusions to facilitateattachment of the frame to the adjacent vertebrae by means ofimpingement into the bone tissue of the adjacent vertebrae.

Further, in some embodiments of the system, the frame may have one ormore receiving elements to accept a locking member for securing theretention member. In various of these particular embodiments, thelocking member may be any of a threaded screw device, a snap lockdevice, or a cam lock device, and further in some of these particularembodiments, the one or more receiving elements for the retention membermay accommodate the temporary location of at least one tissue retractorpin.

Still further, in some embodiments of the system, the frame may beconfigured to receive bone screws there-through to attach the frame tothe vertebrae, the retention member being adapted to cover the bonescrews when the member is attached to the frame to prevent back-out ofthe screws.

In some embodiments of the system, the retention member may beconfigured to retain the interbody implant in its surgically establishedposition.

According to an aspect of the invention, a vertebral implant may beprovided. Embodiments of the implant are configured to rigidlyinterconnect at least two vertebrae, the implant being manufactured froma generally rigid material having thereon contact surfaces for engagingon vertebral bone material, the contact surfaces including abiocompatible, compressible, polymeric material. In some of theseembodiments, the generally rigid material may also include abiocompatible metallic material.

In another aspect of the invention, various embodiments of methods areprovided for applying the system and/or the vertebral implant, assummarized above. In one method of applying the system, the adjacentvertebrae are distracted and spacially oriented with the distractiondevice, the vertebral frame is secured to the adjacent vertebrae, thedamaged tissue is excised through the operating aperture in thevertebral frame, the vertebral interspace is prepared to receive therepair implant, said implant being placed through the operating apertureinto said prepared interspace, and the retention member is theninstalled onto the vertebral frame.

Another embodiment of a method for applying the system is also provided.In this embodiment, the vertebral frame is attached to one or morevertebrae, the vertebrae are then distracted and spacially oriented byoperating through the operating aperture in the vertebral frame, thevertebral frame is secured to each adjacent vertebrae, the damagedtissue is excised through the operating aperture in the vertebral frame,the vertebral interspace is prepared through the operating aperture toreceive the repair implant, the interbody implant is inserted throughthe operating aperture into the prepared interspace and the retentionmember is installed onto the vertebral frame.

In another aspect of the invention, a method for treating a portion of aspinal column is provided. The method includes distracting and spaciallyorienting adjacent vertebral bodies of the spinal column, securing avertebral frame to the adjacent vertebral bodies, the vertebral framehaving at least one operating aperture there-through, preparing avertebral interspace to receive an interbody implant, inserting theinterbody implant through the operating aperture and into the preparedinterspace, and maintaining the vertebral frame in place on thevertebral bodies postoperatively.

In some embodiments of this method for treating a portion of a spinalcolumn, the distracting step is performed using a distraction deviceplaced between the vertebral bodies, and the distraction device isremoved from between the vertebral bodies through the operating aperturein the vertebral frame after the vertebral frame is secured to thevertebral bodies. In some of these methods for treating a portion of thespinal column, the method may further include the step of excisingdamaged tissue through the operating aperture in the vertebral frame. Inanother embodiment, the method may further include the step ofinstalling a retention member onto the vertebral frame after insertingthe interbody implant. In still other embodiments, the step of preparinga vertebral interspace to receive an interbody implant may be performedthrough the operating aperture of the vertebral frame.

In some embodiments of the method for treating a portion of the spinalcolumn, the vertebral frame may have particular features or aspects.Thus, in some embodiments, the vertebral frame may be attached to atleast one of the vertebral bodies before the distraction step, thedistraction step being performed through the operating aperture in thevertebral frame. In other embodiments, the vertebral frame may besecured to more than two adjacent vertebral bodies. In still otherembodiments, the vertebral frame may be maintained in place permanently,generally from the time it is first secured to the vertebral bodies.

According to some aspects of the present invention, a means and methodto precisely control and permanently maintain the preferred spatialrelationship of adjacent vertebral members prior to the surgical removalof damaged tissue may be provided.

According to some aspects of the invention, a means may be providedwhereby preferred spatial relationship of adjacent vertebra can beachieved and permanently maintained using conventional vertebraldistraction methods or in conjunction with a novel intervertebraldistractor apparatus disclosed separately in the co-pending patentapplication Ser. No. 60/954,507 titled “Device and Method for VariablyAdjusting Intervertebral Distraction and Lordosis” filed on Aug. 7,2007.

According to some aspects of the invention, the surgical removal ofdamaged tissue may be constrained in order to minimize the risk ofdamage to the adjacent tissue.

According to some aspects of the invention, the preferred spatialrelationship of adjacent vertebral members may be precisely controlledand permanently maintained with a device having a low profile, allowingthe surgeon to work in an unrestricted manner, within, around, above andbelow the device.

According to some aspects of the invention, the preferred spatialrelationship of adjacent vertebral members may be precisely controlledand permanently maintained for the insertion of a spinal repair device.

According to some aspects of the invention, the insertion of a spinalrepair device may be spatially controlled.

According to some aspects of the invention, a locking member may beaccommodated to prevent undesirable migration of the spinal repairdevice and bone screws.

According to some aspects of the invention, the method and device may beutilized across one or multiple vertebral segments.

According to some aspects of the invention, a permanent rigid internalfixation may be provided across one or multiple vertebral segments.

In one particular embodiment, a permanent semi-rigid fixation isprovided across one or multiple vertebral segments.

In one particular embodiment, a retractor apparatus is accommodated byproviding integrally manufactured receiving and engaging means for thetissue control blades of said retractor.

In one particular embodiment, removable templates which locate andconstrain the surgical removal of tissue to the desired vertebral areaare accommodated.

In one particular embodiment the vertebral fixation element in thesystem is manufactured using two biocompatible materials, the structuralcomponent being manufactured from a high modulus rigid material such asTitanium, Stainless steel or other metal and having therein contactelements for engaging on the vertebral tissue, said contact pads beingmanufactured from a bio-compatible compliant material such aspolyethylene or a silicone. These contact pads are intended to beplastically deformed under compressive loads and to be compressed anddeformed by the insertion of the bone screws in order to act as dampingelements to absorb vibration during bone tissue removal and consequentlyto minimize the risk of associated screw dislocation. These pads furtherincrease the initial friction between the vertebral fixing element andthe vertebrae thereby reducing premature dynamic compression of thedistracted vertebrae. Finally, the compliant elements act as shockabsorbers during patient healing and promote osteogenesis within theimplanted repair device.

In one particular embodiment, the inventive device may be coupled with astereotactic navigational system for preferred device positioning and toconstrain the surgical removal of tissue.

According to aspects of the invention, a system and surgical method foruse in surgical spinal repair or reconstruction procedures are describedherein, whereby preferred and final vertebral axial and angularpositioning and fixation occurs prior to the cutting and removal of thetissue.

In one embodiment, the system can generally be described as acombination of:

-   -   1) An intervertebral distraction device placed temporarily        between adjacent vertebrae for purposes of achieving a desired        spatial relationship between adjacent vertebrae.    -   2) A vertebral plate.    -   3) A locking and retention member engaging with said vertebral        plate.    -   4) An implantable interbody repair device.    -   5) Bone screws.    -   6) The vertebral plate having through holes for the purposes of        accommodating attachment to the vertebrae using the bone screws.    -   7) Said vertebral plate having a generally open interior volume        through which the removal of damaged tissue is performed.    -   8) Said vertebral plate having a generally open interior volume        which constrains the insertion and prevents migration of an        intervertebral repair device.    -   9) Said vertebral plate having accommodation means for attaching        the locking and retention member for retention of the implanted        repair device and the bone screws.    -   10) One embodiment of the surgical method may be generally        described as the sequence of spacially orienting adjacent        vertebrae, locking said vertebrae in their prescribed relative        positions using the vertebral plate and bone screws, preparing        and repairing the intervertebral space through the operating        window in the installed vertebral plate and securing the implant        in place by securing a locking member to the vertebral plate.    -   11) An alternate surgical method may be generally described as        the sequence of attaching the vertebral plate to one of the        adjacent vertebrae, spacially orienting the adjacent vertebrae        through the operating window in the vertebral plate, locking        said vertebrae in their prescribed relative positions using the        vertebral plate and bone screws, preparing and repairing the        intervertebral space through the operating window in the        installed vertebral plate and securing the implant in place by        securing a locking member to the vertebral plate.    -   12) In an alternate surgical method, the vertebrae are partially        distracted and held in this position by the insertion of bone        screws through slots in the vertebral plate. In this instance        the final distraction is achieved by the forcible insertion of        an interbody repair device which has a cranio-caudal dimension        that is larger than the dimension of the receiving        intervertebral space. The differences in the two dimensions        results in a further, final distraction of the adjacent        vertebrae. This final movement of the vertebrae is accommodated        by the movement of the screws within the slots in the vertebral        plate.

In an anticipated procedure a conventional intervertebral distractorapparatus is manually inserted into or between the vertebrae resultingin axial distraction of the vertebrae. In the case of a standard wedgestyle distractor the degree of distraction results from a combination ofthe included angle and the depth to which it is inserted between thevertebrae. In the case of a distractor pin system the distractionresults from the manipulation of a secondarily applied axial adjustmentdevice.

In a further embodiment the included angle of the distractor device isvariably adjustable by the surgeon after insertion between thevertebrae, this adjustment being achieved mechanically by means of ascrew adjustment or the use of another adjusting tool. Such a distractordevice is disclosed in application Ser. No. 60/954,507 titled “Deviceand Method for Variably Adjusting Intervertebral Distraction andLordosis” filed Aug. 7, 2007.

In a further embodiment the distractor apparatus can be mated with astereotactic navigational device to establish, monitor and control thepositioning of the device relative to the adjacent vertebra.

After distraction and lordotic adjustment has been achieved the spinalbridge is located on the vertebrae relative to the distractor device andattached to the adjacent vertebra by at least two bone screws, securingthe vertebrae in their prescribed positions.

If intervertebral distractor devices have been employed they areremoved, exposing a predefined accessible and constrained operatingfield allowing the controlled cutting and removal of tissue to occur.

In a further embodiment the vertebral plate can accommodate insertablecontrol templates which can be placed within it by the surgeon tofurther assist precise tissue removal.

In a further embodiment the vertebral plate can serve as a mounting basefor the attachment of soft tissue retractors, further aiding the surgeonby assuring an un-impeded surgical field.

In a further embodiment the vertebral plate can be removed after theplacement of a disc arthroplasty device.

The intervertebral repair device may be generally wedge shaped, it mayhave an initial radius or taper for engagement with the adjacentvertebrae or it may be conically or cylindrically shaped.

Further, this device may have surface contours thereon which areintended to increase the surface area of contact between said surfacesand the exposed cancellous bone tissue and to increase the intimatecompressive engagement with said cancellous tissue so as to induce andencourage osteogenesis therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows the typical sequence of steps in a current surgicalprocedure.

FIG. 1 b shows the sequence of one embodiment of the inventive methodherein.

FIG. 2 a is an anterolateral isometric view of a single levelimplantable bone plate.

FIG. 2 b is a posterolateral isometric view of a single levelimplantable bone plate.

FIG. 3 a is an anterior isometric view of a multi-level implantable boneplate.

FIG. 3 b is a lateral isometric view of a multi-level implantable boneplate.

FIG. 4 is an oblique perspective view of a multi-level bone plate.

FIG. 5 illustrates a retention member relative to the vertebral frame.

FIG. 6 depicts a retention member in an installed position on thevertebral frame.

FIG. 7 is an anterior (surgical) view of a vertebral frame in itsinstalled position on adjacent vertebrae.

FIG. 8 is an anterolateral perspective view of the vertebral frame inits installed position on adjacent vertebrae.

FIGS. 9 and 10 depict a retention member in-situ after installation ontothe vertebral plate.

FIGS. 11A-11E show another embodiment of an implantable bone plate.

FIG. 11F is a side view showing an exemplary bone screw for use with theimplantable bone plate of FIGS. 11A-11E.

FIGS. 12A-12F show an exemplary cover plate for use with the implantablebone plate of FIGS. 11A-11E.

FIG. 12G is a perspective view showing an exemplary locking arm for usewith the cover plate of FIGS. 12A-12F.

FIGS. 13A-13G show an exemplary instrument guide tool for use with theimplantable bone plate of FIGS. 11A-11E.

FIGS. 14A-14C show an exemplary tissue retractor being used with animplantable bone plate mounted on a vertebral body.

FIGS. 15A-15C show an exemplary interbody repair implant.

FIGS. 16A-16C show an exemplary intervertebral distraction device.

FIGS. 17A-17X show an exemplary spinal fusion surgical procedure.

DETAILED DESCRIPTION

FIG. 1 a describes the typical operational sequence currently employed,wherein vertebrae are distracted, tissue is excised, an implant inplaced between adjacent vertebrae and a bone plate is attached. FIG. 1 bdescribes the preferred operational sequence associated with thisinvention, wherein vertebrae are distracted and placed in theirpreferred relative angular positions and a vertebral frame is attachedto adjacent vertebrae using bone screws to maintain the prescribedspatial relationship during the subsequent steps. In an alternativesequence, the vertebral frame may be attached to adjacent vertebraeprior to distraction and preferred positioning. Thereafter tissue isexcised though the aperture in the frame, the implant is insertedthrough said aperture. A retaining member may be attached to saidvertebral frame to maintain the position of the implanted insert and toprevent back-out of the bone screws.

FIGS. 2 a and 2 b depict a single level vertebral frame 100, intended tosecure two adjacent vertebrae. The device has surfaces 101 and 102 whichare generally contoured to engage positively with the anterior surfacesof the adjacent vertebrae. The device has through holes 103 and 104intended to accommodate the insertion of bones screws into the vertebraltissue. Holes 104 may be elongated to accommodate post surgery dynamicsettling of the vertebrae. The device further has one or more holes 105intended for receiving screws (or other fixation devices) securing theretaining member thereto or there-through. The receiving holes 105 alsoprovide a mounting means for the insertion of temporary soft tissueretractor pins. The device has an operating window defined by the sidewalls 106, 107, 108 and 109. This window is intended to allow unimpairedaccess to the intervertebral space in order to excise tissue andsubsequently to allow the insertion of the interbody repair devicethere-through.

FIG. 3 a depicts a multi-level vertebral frame 200, intended tofacilitate the orientation, fixation and repair of three or morevertebrae.

FIG. 3 b depicts a side view of a multilevel device and illustrates thepresence of a receiving means 201 on the vertebral frame, therebypermitting the plate to accommodate the location and retention of softtissue retractor blades.

Referencing FIGS. 4 and 5; the retention member 300 has a posteriorsurface 301 contoured to match the anterior surface of the vertebralframe 200 and through holes 302 which align with the receiving holes 105in the vertebral frame, these holes being intended to secure theretention member 300 to the vertebral frame 200 in order to retain theinterbody implant in position and to prevent the back-out of the bonescrews used to secure frame 200 to the vertebral bone tissue.

FIG. 6 shows retention member 300 installed to the vertebral frame 200,the anterior surface of the retention member having a contour 401 whichgenerally matches that of the vertebral frame 200 to create a smooth,continuous surface after installation.

FIG. 6 further shows the retention member having extensions 420 thatcover the bone screws and thereby preventing screw back-out.

FIG. 7 depicts the vertebral frame in position on adjacent vertebrae andillustrates the operating window in the region of the disk space. Theoperating window is defined by the cross members 503, 504, 505 and 506respectively which produce a contained area through which all proceduresmay be executed. Further, these members act to restrain the surgeonduring tissue excision and thereby minimize the risk of accidentaldamage to surrounding tissue.

FIG. 7 further illustrates how the device provides access to facilitatethe removal of disk material 502 and the preparation of theintervertebral space 501 prior to the insertion of the interbodyimplant.

FIG. 8 is a perspective side view of the vertebral frame in theinstalled position on adjacent vertebrae. The device has clearancespaces 601 in the region of the disk material to accommodate a betterfit to the vertebral surfaces and to provide additional clearance toallow for the removal of unwanted bone material after deviceinstallation.

FIGS. 9 and 10 depict the retention member 300 placed in-situ on thevertebral frame 200 after the insertion of the interbody implant. Themember 300 is located so as to prevent substantial movement of theinterbody implant and thereby promote bone tissue growth therein.

Instead of screws, or in combination therewith, one or more snap lockdevices may be used to attach retention member 300 to vertebral frame200. Such devices may employ a compressible feature, such as a splitbarb, that locks into place when inserted sufficiently into hole 105 orother mating feature. By using snap lock device(s), member 300 can besimply aligned with frame 200 and pressed into place without requiringthe surgeon to align screws and install them with a driver. One or morecam lock devices may also be used, alone or with screws and/or snap lockdevices. In some cam lock embodiments a torsional force is applied to acomponent, inducing rotation and causing it to become engaged in acorresponding feature within a receiving element. This twisting actioncauses the component to turn and lock under another component, againwith less effort than required when installing a screw.

The system offers substantial benefits over those previously disclosedand those currently employed. These benefits include, but are notlimited to:

1) A novel method which allows for precise control and fixation ofoptimal vertebral position.

2) Constrained and controlled tissue removal

3) Elimination of patient to patient variation

4) Integration of soft tissue retraction devices

5) Reduction in surgical time and maneuvers throughout the case.

Referring to FIGS. 11-16 another exemplary embodiment of an implantablevertebral frame system and method of use will be described. FIGS.11A-11F show the vertebral frame itself and the associated screws ofthis embodiment. Frame 700 is similar in construction and method of useto previously described frame 100. In this embodiment, frame 700 iscurved in the mediolateral direction (as best seen in FIG. 11E) andgenerally straight in the craniocaudal direction (as best seen in FIG.11D) to match the anterior surfaces of adjacent vertebrae to which frame700 will be affixed. In other embodiments, the frame may also be curvedin the craniocaudal direction. In some embodiments it is desirable tohave the radius or radii of curvature as small or smaller than theassociated radii of the adjacent vertebrae to ensure that the frame doesnot wobble when mounted on the vertebrae. In some embodiments, frame 700has a radius of curvature of about 25 mm, an overall length of about 25mm, an overall width of about 19 mm, and a plate thickness of about 2.5mm. It is

Frame 700 includes four bone screw holes 702 extending through frame 700from its anterior face 704 to its posterior face 706. As best seen inFIG. 11A, the anterior side of each hole 702 may be provided with aspherically curved countersink 708. Spherical countersink 708 mates witha complementary shaped spherical shoulder 710 on bone screw 712, asshown in FIG. 11F. Countersink 708 and shoulder 710 cooperate to allowbone screw 712 to be inserted through screw hole 702 in a wide range ofmediolateral and craniocaudal angles while still allowing the head 714of screw 712 to remain firmly seated against frame 700 when installed toprevent movement of frame 700. As best seen in FIG. 11D, bone screwholes 702 and countersinks 708 can be configured to provide nominalscrew angles such that screws 712 angle away from each other in thecraniocaudal direction. As best seen in FIG. 11E, bone screw holes 702and countersinks 708 can be configured to provide nominal screw anglessuch that screws 712 angle towards each other in the mediolateraldirection. While the spherical countersinks 708 allow the surgeon tovary the screw angle from nominal as previously described, these nominalcompound screw angles allow frame 700 to withstand greater extractionforces in the anterior direction than if each screw were perpendicularto frame 700, thereby allowing frame 700 to be affixed to the adjacentvertebral bodies more rigidly.

Referring to FIGS. 11A and 11B, frame 700 also includes an operatingaperture 716 through its midsection, the purpose of which will be laterdescribed. In this exemplary embodiment, operating aperture 716 has aheight of about 10.5 mm and a width of about 15 mm. Coplanar referencesurfaces 718 may also be provided, such as along the longitudinalcenterline of frame 700 on opposite sides of operating aperture 716 asshown. Surfaces 718 may be held to high tolerances to provide accuratedatum points for surgical tools and a cover plate that will be laterdescribed. Slotted through holes 720 or similar features may be providedon opposite sides of operating aperture 716 to allow frame 700 to beplaced over distractor pins located in adjacent vertebrae. Slotted holes720 may also serve as additional datum points. In this exemplaryembodiment, all other critical features of frame 700 are formed inreference to surfaces 718, holes 720, and the edges of operatingaperture 716 adjacent to surfaces 718. Frame 700 may be provided withindents 722 along the longitudinal centerline of frame 700 to aid thesurgeon in placing frame 700 on the centers of adjacent vertebralbodies.

Referring to FIGS. 11A and 11C-11E, recesses 724 may be provided in eachcorner of frame 700 as shown for anchoring mating prongs of soft tissueretractors, as will be subsequently described in more detail. As shownin FIG. 11C, an anteriorly extending pocket 726 may be formed in thegenerally posteriorly facing surface of each recess 724 to morepositively engage the mating prongs of the retractors.

Referring to FIGS. 11A and 11C, two pairs of opposing undercuts 728 and730 are shown on the posterior face 706. The first pair of undercuts 728are on mediolaterally opposite sides of operating aperture 716 and eachhave a posteriorly facing surface located between the anterior face 704and posterior face 706 of frame 700. These undercuts 728 serve toreceive snap-fit protrusions of a cover plate to temporarily hold it inplace, as will be subsequently described in more detail. The second pairof undercuts 730 are on craniocaudally opposite sides of operatingaperture 716 and also each have a posteriorly facing surface locatedbetween the anterior face 704 and posterior face 706 of frame 700. Theseundercuts 730 serve to receive the distal ends of a rotatable lockingarm of the cover plate to permanently hold the cover plate in place, aswill also be subsequently described in more detail.

Referring to FIG. 11F, a proprietary bone screw 712 may be used with theinventive frame 700. Screw 712 includes a head 714 and a threaded shank732. Threaded shank 732 may be configured to be self drilling and/orself tapping. As previously described, screw 712 also includes ashoulder portion 710. Screw 712 may be provided with head relief portion734 to cooperate with a screw locking portion of a cover plate, as willbe subsequently described in detail.

As shown in FIGS. 11A-11E, the vertebral frame 700 in this embodiment iscompletely symmetrical about the longitudinal and transversecenterlines. This allows the surgeon to install the plate on thevertebrae without having to first determine a proper craniocaudalorientation.

Referring to FIGS. 12A-12G, an exemplary cover plate 750 configured tointerface with vertebral frame 700 is shown. In this exemplaryembodiment, cover plate 750 serves to prevent an intervertebral implantfrom moving anteriorly, and prevents screws 712 from backing out of thevertebral bodies.

Cover plate 750 may be curved in mediolateral direction, as best seen inFIG. 12F, to generally match the curvature of frame 700. In thisexemplary embodiment, cover plate has an anterior side 751 and aposterior side 753. Cover plate 750 may include a pair of opposingmediolateral wings 752 and a pair of opposing craniocaudal wings 754.When cover plate 750 is installed on frame 700, the central portion ofcover plate 750 and the mediolateral wings 752 are received within theoperating aperture 716 of frame 700 and serve to cover aperture 716.Mediolateral wings 752 each comprise a laterally extending arm 756 witha tongue 758 located at its distal posterior edge. Each tongue 758 isengagable with one of the previously described opposing undercuts 728 offrame 700. This arrangement allows a surgeon to snap cover plate 750 inplace and have it temporarily held in place by tongues 758 locking intoundercuts 728. In this embodiment, arms 756 have some resiliency,allowing them to flex as tongues 758 begin entering operating aperture716 and before entering undercuts 728. Craniocaudal wings 754 coverreference surfaces 718 of frame 700 when installed. Additionally, distalportions 760 of craniocaudal wings cover a portion of screw heads 714,as will be subsequently described in more detail. As best seen in FIG.12C, distal portions 760 include undercuts 762 for engaging head reliefportions 734 of screws 712.

Referring to FIG. 12G, a locking arm 764 configured for permanentassembly with cover plate 750 is shown. Locking arm 764 may be a unitarymember that snaps into a central bore of cover plate 750, or maycomprise a separate arm that is swaged, press fit or otherwise fixedlysecured to locking socket 766 before or during assembly with cover plate750. Once assembled, locking arm 764 is rotably retained on cover plate750 with locking socket 766 accessible from the anterior side 768 ofcover plate 750, as shown in FIGS. 12A and 12B. Locking arm 764, whichis driven by locking socket 766, is located on the posterior side 770 ofcover plate 750, and is rotatable between a locked position, as shown inFIG. 12C, and an unlocked position, as shown in FIG. 16S. When in thelocked position, the distal ends of locking arm 764 are received withinthe second pair of undercuts 730 on opposite ends of operating aperture716 in frame 700, shown in FIG. 11A. In this position, cover plate 750is securely locked to frame 700 since reference surfaces 718 (FIG. 11A)are captured between locking arm 764 and the craniocaudal wings 754 ofcover plate 750 (FIG. 12C). In other embodiments (not shown), thelocking arm engages the frame on opposite mediolateral sides instead ofcraniocaudal sides.

Locking arm 764 may include a raised dimple 768, as shown in FIG. 12G,that extends from the locking arm towards the underside of cover plate750. Cover plate 750 may be provided with a through-hole 770, as shownin FIG. 12D, for receiving the raised dimple 768 when locking arm 764 isin the locked position. Cover plate 750 may also be provided with aramped recess 772 adjacent to hole 770. Recess 772 becomes deeper as itextends away from hole 770. This arrangement biases locking arm 764toward the unlocked position as dimple 768 is urged toward the bottom ofthe ramp at the opposite end of recess 772 from hole 770. Thisarrangement also provides better tactile feedback to the surgeon, whofeels increasing resistance when turning locking socket 766, untildimple 768 snaps into hole 770. Dimple 768 and/or locking arm 764 mayhave a different color that contrasts with cover plate 750 to providevisual feedback through hole 770 when locking arm 764 is in the fullylocked position. Dimple 768 and arm 764 may be configured to click whenentering hole 770. Accordingly, the surgeon may be provided withtactile, visual and audible confirmation when arm 764 is in the fullylocked position.

Through hole 774 may be provided in locking arm 764, as shown in FIG.12G, to align with blind hole 776 in cover plate 750, as shown in FIG.12D, when locking arm 764 is in the unlocked position. Holes 774 and 776may be used in conjunction with assembly tooling (not shown) when coverplate 750 is being manufactured. Raised portions 778 may be provided onthe posterior side of cover plate 750, as shown in FIGS. 12C and 12D, tolimit the travel of locking arm 764. In some embodiments, the travel ofarm 764 between the unlocked and locked positions is about 45 degrees.

Cover plate 750 may be made of PEEK so as to be radiolucent. This allowsbone growth into an implant beneath cover plate 750 (as will besubsequently described) to be viewed with various imaging techniques.Locking arm 764 may be made of titanium so its locked status can beconfirmed by imaging.

Referring to FIGS. 13A-13G, an exemplary instrument guide 800 configuredfor use with vertebral frame 700 is shown. Instrument guide 800 has aproximal end 802 and a distal end 804. A handle 806 may be provided forholding guide 800 in place during a surgical procedure. In someembodiments, a removable divider or insert 808 is configured to bereceived within guide 800.

As best seen in FIG. 13E, instrument guide 800 includes a tri-lobe lumen810 extending therethrough from the proximal end 802 to the distal end804. Lumen 810 includes a central bore 812 overlapping two lateral bores814.

The distal end 804 of guide 800 is configured to mate with the anteriorside 704 of vertebral frame 700. As best seen in FIGS. 13A and 13G,distal end 804 may be curved in the mediolateral direction to match thecurvature of frame 700. As best seen in FIGS. 13C and 13D, the body (andtherefore lumen 810) of guide 800 may be angled in the caudal directionrelative to the distal end 804. In some embodiments, this angle is about3 degrees to correspond with the angle of the interverbral spacerelative to the anterior surface of vertebral bodies in the cervicalspine. When guide 800 is coupled to frame 700, lumen 810 of guide 800lines up with operating aperture 716 of frame 700.

Referring to FIGS. 13E-13G, features of the distal end 804 of guide 800are shown. Registration surfaces 815 are provided on guide 800 forcontacting reference surfaces 718 of frame 700, shown in FIGS. 11A and11B. Bosses 816 may be provided on registration surfaces 815 as shownfor engaging holes 720 in reference surfaces 718. The above featurescooperate to accurately align features on guide 800 that may becritical, such a lumen 810 and proximal surface 802, with features onframe 700 and underlying anatomical features.

Insert 808 has rounded sides corresponding with central bore 812, asbest seen in FIG. 13B. When optional insert 808 in temporarily placed incentral bore 812 in this exemplary embodiment, the tri-lobe lumen ofguide 800 is converted into two individual lateral bores 814 as shown.Insert 808 may be provided with a handle 818. In this embodiment, handle818 includes an elongated rib 820 which is received in slot 822 in theguide body, as shown in FIG. 13A. This arrangement allows insert 808 tobe keyed with guide 800 in only one orientation. Insert handle 818 mayalso be provided with a direction indicator, such as an arrow pointingto the patient's feet and corresponding indicia, as shown in FIG. 13B.

Referring to FIGS. 14A-14C, an exemplary soft tissue retractor 830constructed according to aspects of the invention is shown. One or moreretractors 830 may be used in conjunction with intervertebral frame 700after it is installed on one or more vertebrae to retract soft tissueaway from frame 700 during a surgical procedure. Retractor 830 includesa blade 832. The distal end of blade 832 may be provided with a fulcrum834 for contacting vertebral body 836, and a pair of tongues 838 forengaging with previously described recesses 724 in frame 700. The distalends of tongues 838 may be provided with protrusions 840 projecting inthe anterior direction for engaging with previously described pockets726 in recesses 724. As shown in FIG. 14A, the distal end of blade 832may be placed adjacent to frame 700, and then tongues 838 may beinserted into recesses 724 as shown in FIG. 14B. The proximal end ofblade 832 may be provided with a feature, such as hole 842 in flange844, for attaching a handle or spreading device (not shown) to urge theproximal end of blade 832 in a lateral direction against soft tissueadjacent to frame 700. A single spreading device may be attached betweena pair of opposing retractors 830 (only one shown for clarity) to keepthem spread apart. Blade(s) 830 may be curved, as shown in FIG. 14C,and/or may be provided with a longitudinal rib 846, as shown in FIGS.14A and 14B, for increased rigidity.

Referring to FIGS. 15A-15C, an exemplary interbody repair implant 850constructed according to aspects of the invention is shown. In thisembodiment, implant 850 has an elongated tri-lobe shape which includes acentral cylindrical portion 852 and two lateral cylindrical portions 854which overlap with the central portion 852. Cylindrical portions 852 and854 correspond with central bore 812 and overlapping lateral bores 814,respectively, of instrument guide 800. Implant 850 may be provided withone or more graft windows 856 for receiving cages containing bonematerial and/or for promoting bony ingrowth between the vertebrae andimplant 850. One or both ends of implant 850 may be provided with acentral hole 858 and two lateral holes 860, or other suitable features,for engaging implant insertion instrumentation. In this exemplaryembodiment, central hole 858 is threaded and lateral holes 860 areconfigured for sliding engagement with features on the instrumentation.One or more radio markers 862 may be provided on implant 850, such asshown in the four corners of the implant in FIGS. 15B and 15C. Radiomarkers 862 may comprise titanium, tantalum or other biocompatible,radio-opaque material(s) to assist in determining the position ofimplant 850 in imaging.

In some embodiments, the tri-lobe configuration of implant 850 helpsresist undesirable axial rotation between axial vertebrae. In someembodiments this configuration minimizes the tissue that is removed fromthe adjacent vertebrae as compared with a rectangular or other shapeimplant. In some embodiments surgeons are provided with implants thatare either 11 mm or 15 mm long, and 15 mm or 18 mm wide.

In some embodiments implant 850 is made of PEEK. Since PEEK isradiolucent, bony ingrowth into the implant may be monitored withimaging during the healing process. In other embodiments, the implantcomprises titanium and/or stainless steel.

Referring to FIGS. 16A-16B, an exemplary intervertebral distractiondevice 870 constructed according to aspects of the invention is shown.Distraction device 870 includes a wedge portion 872 and a head portion874. In this embodiment, wedge portion 872 includes a first pair ofnon-parallel surfaces 876, 878, and a second pair of non-parallelsurfaces 880, 882. First surfaces 876 and 878 serve as lead-in surfaceswhen distraction device 870 is being introduced between the endplates ofadjacent vertebral bodies. Second surfaces 880 and 882 serve to orientthe vertebral endplates at a predetermined distraction distance h andlordosis angle α.

Head portion 874 of distracton device 870 may have a height H in acraniocaudal direction larger than the height h of wedge portion 872 inthe same craniocaudal direction, as shown in FIG. 16C. This preventshead portion 874 from entering the intervertebral space between theadjacent vertebrae. In other words, shoulders 884 serve as a depth stopby contacting the anterior surfaces of the vertebrae, as will besubsequently described in more detail. In some embodiments, the surgicalteam may be provided with a kit comprising distraction devices eachhaving the same head height H and different wedge portion heights h,such as 4, 5, 6, 7, and 8 mm. As can also be seen in FIG. 16C, wedgeportion 872 has a predetermined length L, which in some embodiments is10 mm. Wedge portion 872 has a longitudinal axis that in someembodiments is not perpendicular to shoulders 884. In this exemplaryembodiment, the angle of offset between wedge portion 872 and headportion 874 matches the previously described angle of the body (andtherefore lumen 810) of guide 800 relative to the distal end 804. Insome embodiments, this angle is about 3 degrees to correspond with theangle of the interverbral space relative to the anterior surface ofvertebral bodies in the cervical spine.

Head portion 874 of distracton device 870 may be provided with a centralhole 858 and two lateral holes 860, or other suitable features, forengaging implant insertion instrumentation as previously described inrelation to interbody repair implant 850.

Referring to FIGS. 17A-17X, an exemplary spinal fusion surgicalprocedure using the previously described components is depictedaccording to aspects of the invention.

FIG. 17A shows an exemplary distraction device 870 temporarily attachedto an insertion instrument 900 and about to be inserted between adjacentvertebrae 836, 836. Insertion instrument 900 may include a separateshaft portion 902 removably attached to a handle 904, such as a handlehaving a standard “AO” interface.

FIG. 17B shows distraction device 870 inserted between adjacentvertebrae 836, 836 as the insertion instrument is being removed.

FIG. 17C shows a cross-section of distraction device 870 insertedbetween adjacent vertebrae 836, 836 after the insertion instrument hasbeen removed.

FIG. 17D shows intervertebral frame 700 placed on adjacent vertebrae836, 836 over distraction device 870. Operating aperture 716 throughframe 700 can be configured with a craniocaudal height just nominallylarger than the craniocaudal height of head 874 of distraction device870. This arrangement allows a surgeon to properly center frame 700 overthe intervertebral space 906 between adjacent vertebrae 836, 836 merelyby placing frame 700 over head 874. As previously described, indents 722at the top and bottom of frame 700 can provide assistance to the surgeonwhen centering frame 700 in the mediolateral direction.

FIG. 17E shows a drill guide 908 placed over one of the screw holes 702in frame 700 for guiding optional drill 910 to create holes in vertebrae836 for receiving bone screws. A reamer, tap and/or other bone cuttinginstruments may also be optionally used to prepare screw holes. In someembodiments, self drilling and/or self-tapping screws may be used. Thescrews may be installed by hand or with a screw guide similar to drillguide 908. The screws may be fixed angle and/or variable angle. In someembodiments, the screws have an aggressive thread. In some embodiments a4.0 mm standard size screw is used. In some embodiments a 4.5 mmrecovery screw is used.

FIG. 17F shows frame 700 secured to adjacent vertebrae 836, 836 withfour screws 712.

FIG. 17G shows frame 700 secured to adjacent vertebrae 836, 836 afterdistraction device 870 has been removed. Distraction and lordotic angleis now permanently set and locked in place by frame 700.

FIG. 17H shows frame 700 secured to adjacent vertebrae 836, 836 withretractor 830 attached and instrument guide 800 being lowered intoposition on top of frame 700.

FIG. 17I shows instrument guide 800 in position on top of frame 700 anda large drill 912 being inserted into central bore 812 of guide 800 tobegin preparing the intervertebral space between vertebrae 836, 836 byremoving the disc and/or end plate material. A drill, trephine, reamer,other bone cutting tool, or a combination thereof may be used to preparethe intervertebral space. Standard sizes of 6, 7, 8 or 9 mm can all beproduced using the same instrument guide. In some embodiments a customcutter is used with cutting sides and face. In some embodiments, thenatural bone material being removed is collected from the cuttingtool(s) and packed into the interbody implant before it is implanted inthe patient.

FIG. 17J shows instrument guide 800 in position on top of frame 700 andguide insert 808 being inserted into central bore 812 of guide 800.

FIG. 17K shows instrument guide 800 in position on top of frame 700 andguide insert 808 fully inserted into central bore 812 of guide 800.

FIG. 17L shows instrument guide 800 in position on top of frame 700 anda small drill 914 being inserted into one of the lateral bores 814 ofguide 800 to further prepare the intervertebral space between vertebrae836, 836. As with the central bore, a drill, trephine, reamer, otherbone cutting tool, or a combination thereof may be used in the lateralbores, and the harvested bone tissue may be packed into the implant. Insome embodiments, the lateral bores are prepared without the use of aninsert 808, and/or the lateral bores may be prepared before or after thecentral bore.

FIG. 17M shows frame 700 secured to adjacent vertebrae 836, 836 with theintervertebral space 906 prepared for receiving a tri-lobeintervertebral implant.

FIG. 17N depicts the nominal diameters (in millimeters) of the centraland lateral bores for preparing the intervertebral space in variousexemplary embodiments. In some embodiments, a variety of implant andguide configurations are made available to the surgical team in a singlekit. Each configuration may have the same overall width. In other words,the distance between the outer circumferences of the lateral boresremains fixed across multiple configurations rather than the distancebetween the centers of the axial bores. Lobe sizes may be surgeonselected based on physiology and disk condition. Standard kerrisons andcurettes may be used through the channel.

In some embodiments, the intervertebral space 906 is configured to benominally smaller than the associated interbody implant, requiring theimplant to compressively engage the vertebrae endplates when implanted.This arrangement can provide immediate structural stability of therepaired spine segment and can promote boney ingrowth into the implant.

FIG. 17O shows an interbody implant 850 attached to an insertion tool900 and being inserted through the operating aperture 716 of frame 700into the prepared intervertebral space. Insertion stops may be providedon the implant and/or insertion tool to limit the depth of insertion ofthe implant.

FIG. 17P shows a craniocaudal cross section of interbody implant 850 inplace in the prepared intervertebral space.

FIG. 17Q shows a mediolateral cross section of interbody implant 850 inplace in the prepared intervertebral space.

FIG. 17R shows cover plate 750 in position over frame 700.

FIG. 17S depicts locking arm 764 of cover plate 750 in the unlockedposition and moving towards the locked position.

FIG. 17T depicts locking arm 764 of cover plate 750 in the lockedposition.

FIG. 17U shows an oblique posterior view of a craniocaudal cross-sectionof cover plate 750 coupled to frame 700 with locking arm 764 in thelocked position.

FIG. 17V shows an oblique anterior view of a craniocaudal cross-sectionof cover plate 750 coupled to frame 700 mounted on adjacent vertebrae736, 736, with locking arm 764 in the locked position.

FIG. 17W shows an oblique mediolateral cross-sectional view of acoverplate 750 coupled to frame 700 and covering a portion of screwheads 714.

FIG. 17X shows a mediolateral cross-sectional end view of a coverplate750 coupled to frame 700 and covering a portion of screw heads 714.

In some embodiments, not every step shown in FIGS. 17A-17X is performed.In some embodiments, additional and/or alternative steps may beperformed.

In summary, an exemplary trans-plate cervical decompression and fusionprocedure may include at least the following steps:

-   -   Anterior incision    -   Retraction    -   Distraction and pre-lordosing    -   Vertebral frame installation over the distraction device    -   Removal of distraction device    -   Discectomy and end plate preparation through the frame    -   Decompression    -   Implant insertion    -   Cover implant and lock    -   Close incision

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

What is claimed is:
 1. A system for establishing and securing adjacentvertebrae in a defined spatial relationship, the system comprising: atleast one implantable vertebral frame configured to span between theadjacent vertebrae, the frame being configured to attach to each of theadjacent vertebra to postoperatively maintain the desired spatialrelationship between the vertebrae, the frame having at least oneinternal operating aperture there-through for providing access to anintervertebral space and exposing endplate tissue of the adjacentvertebrae, the aperture having a width of about 15 mm in a directionsubstantially parallel to the endplate tissue when the vertebral frameis implanted on the adjacent vertebrae, the aperture being elongatedsuch that the width is larger than a height of the aperture, the heightbeing transverse to the width; at least one retention member attachableto the frame to cover at least a portion of the aperture, the at leastone retention member having a locking portion rotatable between anunlocked position and a locked position, the locking portion preventingthe at least one retention member from being separated from the framewhen in the locked position, wherein the locking portion comprises arotatable member and at least one elongated arm that extends radiallyoutward from the rotatable member and is configured to contact aposterior side of the frame when the elongated arm is rotated into thelocked position, and wherein the elongated arm is configured todisengage from the posterior side of the frame when rotated into theunlocked position; and two detent features located on a posterior sideof the retention member, one of the two detent features serving toreleasably hold the locking portion in the locked position and the otherof the two detent features serving to releasably hold the lockingportion in the unlocked position.
 2. The system of claim 1 wherein theat least one elongated arm comprises two elongated arms that contact theposterior side of the frame on opposite sides of the operating aperturewhen the locking portion is in the locked position.
 3. The system ofclaim 1 wherein the at least one retention member further comprises atleast one screw cover portion, wherein the screw cover portion covers atleast part of a screw securing the frame to one of the adjacentvertebrae, the screw cover portion preventing the screw from backing outof the vertebra.
 4. The system of claim 3 wherein the at least one screwcover portion comprises two screw cover portions.
 5. The system of claim3 wherein the at least one screw cover portion comprises four screwcover portions.
 6. The system of claim 1 wherein the at least oneretention member further comprises a transitory locking portion havingat least one resilient arm engageable with the frame for maintaining theat least one retention member on the frame before the locking portion ismoved from the unlocked position to the locked position.
 7. The systemof claim 1 wherein the at least one internal operating aperture throughthe at least one implantable vertebral frame is configured to expose aportion of an anterior surface on each of the adjacent vertebrae whenimplanted thereon.
 8. The system of claim 1 wherein the at least oneelongated arm includes exactly two elongated arms that extend radiallyoutward from the rotatable member in opposite directions and areconfigured to contact the posterior side of the frame when the elongatedarms are rotated into the locked position, and wherein the elongatedarms are configured to disengage from the posterior side of the framewhen rotated into the unlocked position.
 9. The system of claim 1wherein the height of the aperture is about 10.5 mm.